Field
The present disclosure relates generally to touch sensitive systems and more specifically to identifying location(s) of touch events on a touch sensitive system using frequency modulated radiation sources (such as light emitting diodes (LEDs)).
Background Art
Touch panels are provided to detect two-dimensional coordinate information. A touch panel can be an opaque track pad. Another example of a touch panel can include a transparent touchscreen that can be placed in front of a display such as a liquid crystal display. Touch panels can be based on a variety of sensing technologies, for example, resistive, capacitive, surface acoustic wave, infrared (IR) grid, IR acrylic projection, optical imaging, acoustic pulse recognition, etc.
As one example, infrared (IR) touch panels can include an array of X-Y light emitting diodes (LEDs) and detectors. The detectors can detect the two-dimensional coordinate of a touch on the IR touch panel when the touch disrupts the beam of radiation from the LEDs. In this example, the LEDs and the detectors are located on the edges of the IR touch panel. In some conventional IR touch panels, only one of the LEDs is on (emitting light) at a time and therefore, for large size touch panels, where there is a large area to scan, it is technically challenging to achieve a suitably fast response time and minimize the cost.